Ultrasound imaging is an attractive modality for numerous diagnostic procedures because of its non-invasive nature, relatively low cost, and lack of radiation exposure. Medical ultrasound images are typically produced by generating an ultrasonic sound wave traveling in a known direction and observing the echoes created when the sound wave is scattered or bounces off of the boundaries between regions of differing density in the body. For any given direction of the ultrasound beam, the image pixels are generated by plotting a dot whose brightness is proportional to the echo's amplitude at a coordinate whose location is a function of the time after a short ultrasound pulse is send in the direction of the scan line being measured.
While ultrasound has a number of advantages over other measurement modalities, it suffers from noise problems that make the measurements difficult to interpret without some form of noise reduction. This noise results from noise in the receiver and from the individual sound scattering centers in the tissues between the transducer and some structure of interest. While various forms of averaging may be used to reduce the effects introduced by these scattering centers, averaging can do little to distinguish tissues having very similar densities. In addition, many tissues have very similar densities. Hence, generating an image of the boundary between two types of tissues is difficult if the tissues are not separated by a region having a significantly different density.
Broadly, it is the object of the present invention to provide an improved ultrasound imaging system.
It is a further object of the present invention to provide an ultrasound imaging system that can distinguish tissues based on properties other than density.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.